This video shows you how to remove ink stains from carpet. Take it from a professional carpet cleaner working in Tampa FL WD-40 is not something you want in your carpet. It will help remove the ink stains but WD-40 is not water soluble, so it cannot be removed with water. using WD-40 to remove ink stains from carpet is just swapping out stains. The ink will be gone but the carpet fibers will hold onto the grease and start collecting soil almost immediately.
Your better off using a 1:3 mix of hydrogen peroxide and water, or two teaspoons of oxy clean and water to remove ink. They will get the stains out without leaving dirt attracting residues. If that doesn't work you can be a little more adventurous and try using hair spray to remove the ink from the carpet. If you use hair spray make sure to flush it with a lot of water afterwords to remove the extra hair spray.
Another how to remove ink stains from carpet favorite is rubbing alcohol. Alcohol is a solvent and works great on ink and other oily stains. Mix 1/4 cup of rubbing alcohol and 1/4 cup of water together and spray it on the ink spot. If you don't have a sprayer you can pour it directly on the spot. Let it sit for 30 seconds and then start to blot it up with a clean white towel.
Any one of the methods above should remove the ink stain but WD-40 is my least favorite ink remover. If none of these remedies removes the ink stain, then it might be time to call in a professional carpet cleaner.